Reply With QuoteJust lean shouldn't melt the water cooled exhaust hoses. Water flow problem. How did you plumb the headers? I switched from logs to Lightnings this past winter, zero trouble this year, exc engine running about 20 deg COOLER now.
wonder if its runnin lean?? that'd melt tubes and not show up to much on the temp gauge
Just lean shouldn't melt the water cooled exhaust hoses. Water flow problem. How did you plumb the headers? I switched from logs to Lightnings this past winter, zero trouble this year, exc engine running about 20 deg COOLER now.
same setup as last year. I didnt have any issues last year. Im pretty sure its a water flow thing too. My thoughts are somthing plugiging the headers (possibly scaling) or header feed lines. Im a bit sick of the rubber tubes though. I think im going to have some steel tubes fabricated to replace most of the hose.
Does anyone have a picture of or a link to the waterflow through a BBC? Whats the easiest way to get the freeze plugs out without a slide hammer? I think I may be full of sand which is limiting the water flow through the motor and not cooling. It seems like the oil gets hot but not the cooling water. Any Ideas would be helpful.
On another note ..For the short time that I did get to run the boat I went from 4600 rpm to 5000 rpm by changing the manifold and rockers. Acording to the JPC thats a big jump in Horse power. Last year was dominator A impeller 53mph @ 4600rpm. this year I pulled 5000rpm. Didnt get a top speed. Thats like 90 horse gain. Does that seem possible?
Well, Ive had the boat out twice this year. On the first run I had overheating / water flow issues. I found the block was stuffed with mud and the header water manifolds had plugging from scaling. During the short time I ran the boat I thought I gained RMP (misread the guage) but in fact I lost RPM at the top end. At least 200 to 400 rpm from the changes I made (intake and rockers). The second time I went out, after I got all of the mud out and replaced the exhaust hoses, I noticed some strange happenings. When I would accelerate to full speed, if the engine was cool , I could get 4300rmp but the longer I stayed at full throttle the rpm would drop to 4000. If I would drop back to cruse at 3500-3800 for a while I would only be able to accelerate to 4000rmp. If I stop for a few minutes , idle, I can then get back to 4300. Oil pressure is 25psi at Idle when warm. Engine water temp stays below 150 the whole time Any thoughts what would cause the loss of power? This didnt happen last year.
What kinda (make and model) of carbs are you running?
edelbrock i belive 625 (not sure) vacume secondaries
I would like to add my 2 cents based on my experience. If you look at any torque curves on an engine running a dual plane you will find that they drop off at around 2500-3000 rpm. They are very strong from idle but are useless at anything over 3000 rpm. I fell into the trap because the RPM range is idle to 5500 and sounded like it would work. A single plane manifold will make max torque in the 4500-5000 range , right were we drive our boat. I gained about 200-300 rpm going to a single plane manifold.
If I'm reading everything correctly, he is running a single plane now (used to have a dual plane).
Reason I asked about the carbs is just a theory. I wonder if since they're vacuum secondaries that maybe while under acceleration/load the secondaries are opening. Once max speed rpm is reached the secondaries are closing slightly due to less demand/load/vacuum on them?
Just a thought.
Now thats an interesting thought :idea:
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